Updating Reduced Match Criteria for the Forest Restoration & Wildfire Risk Mitigation Grant
Introduction
In 2020, our research team at Colorado State University developed the Wildfire Social Vulnerability Index (WFSVI) in order to set a criteria for reduced match for the Forest Restoration & Wildfire Risk Mitigation (FRWRM) Grant. The data layer was updated in 2023 as described in this report. This report describes the 2024 updates to the WFSVI, which consists of updating the 5-year American Community Survey from (2017-2021) to (2018-2022). Additionally, we provide a version of the WFSVI that is not clipped to WUI only areas.
American Community Survey Update
The original WFSVI was built using 5-year (2016 - 2020) American Community Survey (ACS) estimates. We have updated the WFSVI using the most current 5-year (2018-2022) ACS data. In some cases, no data is reported for a census block group because of poor response to the ACS or insufficient sample size to meet data disclosure requirements. We use two methods to impute missing values. First, if the data is reported at the census tract1, we use the census tract data to fill any missing records. While these data may be less spatially accurate, they represent the next best estimate of the block group value. Second, we use a machine learning imputation model to complete missing records when tract level information is unavailable. The machine learning method is known as random forest and is implemented via missForest package in R. The random forest method uses nonmissing data for one variable to train a model based on other nonmissing variables from other block groups around the state and uses that model to estimate missing values. It applies this procedure to each variable and iteratively updates until the model converges on its best estimate (see the package documentation for more information).
Colorado EnviroScreen Data
Colorado’s Environmental Justice Act (HB21-1266) prompted the development of the EnviroScreen mapping tool to identify “disproportionately impacted communities”. We consider any disproportionately impacted community to automatically qualify for the FRWRM reduced match requirement. According to the EnviroScreen documentation, a disproportionately impacted community is defined as
… census block groups where more than 40% of the population are low-income (meaning that median household income is at or below 200% of the federal poverty line), 50% of the households are housing cost-burdened (meaning that a household spends more than 30% of its income on housing costs like rent or a mortgage), 40% of the population are people of color (including all people who do not identify as non-Hispanic white), or 20% of households are linguistically isolated (meaning that all members of a household that are 14 years old or older have difficulty with speaking English). Also included in this definition are mobile home communities, the Ute Mountain Ute and Southern Ute Indian Reservations, and all areas that qualify as disadvantaged in the federal Climate and Economic Justice Screening Tool. The definition also includes census block groups that experience higher rates of cumulative impacts, which is represented by an EnviroScreen Score (Percentile) above 80.
The CO EnviroScreen tool data was built using 5-year ACS data from 2015-2019 along with many other data sources. However, the current WFSVI is based on the 5-year ACS 2018-2022, which are based on census block groups redefined in 2020. Consequently, the CO EnviroScreen tool data cannot be directly merged with the WFSVI data. We use a geographic crosswalk designed to harmonize data across time (Manson et al., 2021). The crosswalk develops a set of weights based on the estimated fraction of the population or households in the 2010-2020 block group definition to the 2020 block group definition. We use the population weights to translate the following data between block group definitions: low-income, people of color, the cumulative impact score, and the Justice 40 criteria, and the household weights to map the housing burden and linguistic isolation criteria. We then apply the qualifying thresholds defined above to determine which of the 2020 block groups qualifies as a disproportionately impacted community.
The integration of the CO EnviroScreen tool aligns the WFSVI with HB21-1266 in Colorado and the federal Justice 40 initiative. Future versions of the WFSVI will include Colorado EnviroScreen 2.0, which is currently under development.
Updated WFSVI Layer
The 2024 update of the WFSVI layer includes a version clipped to census block groups (CBG) that include WUI (comparable to previous years), and an unclipped version that includes all CBGs regardless of WUI. The version used to inform the reduced match for FRWRM is clipped to the WUI because only WUI areas qualify for the program. The version clipped to the WUI includes a variable indicating that a CBG qualifies for the reduced match while the unclipped version only includes the WFSVI score. Otherwise, the layers contain the same information.
Method Update: Previous versions of the WFSVI calculate percent rank scores (i.e., percentile) for each index component using only the subset of CBGs with WUI (see report). The current version calculate percent rank scores for the index components using every CBG in the state. The percent rank is a relative metric and depends on the set of values a particular CBG is being compared. We implement this change in method to create a consistent WFSVI between the WUI-clipped and unclipped versions. Therefore, WFSVI scores, and thus CBGs qualifying for reduced match in FRWRM, may differ from last year because of changes in the American Community Survey data and the set of CBGs used to calculate the WFSVI.
WFSVI-WUI
The WFSVI-WUI is the version clipped to CBGs with WUI and should be used for the FRWRM grant.